Lesson Notes By Weeks and Term v4 - SHS 3
Organic Functional groups
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Organic Functional groups
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Subject: Chemistry
Class: SHS 3
Term: 2nd Term
Week: 12
Grade code: 1.3.2.LI.2
Strand code: 3
Sub-strand code: 2
Content standard code: 1.3.2.CS.1
Indicator code: 1.3.2.LI.2
Theme: CHEMISTRY OF CARBON COMPOUNDS
Subtheme: Organic Functional groups
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Welcome, future scientists and engineers! Today, we are exploring a fundamental concept in organic chemistry called the homologous series. Think about a large family, like the Ofori-Atta family or the Adu-Boahen family. Members of the same family share a common name, similar features, and certain family traits. Similarly, organic compounds can be grouped into "families" called homologous series. Understanding these families helps us to predict the properties and reactions of millions of organic compounds in an organised way. This is very important in our daily lives in Ghana.
A. Ways of Representing Organic Compounds
Before we can discuss families of compounds, we need to know how to draw and write them. There are three main ways: Molecular Formula: Shows the actual number of atoms of each element in one molecule. It tells you *what* and *how many*, but not *how they are connected*. Example: Propane is `C₃H₈`. Structural Formula: Shows every atom and every bond in the molecule. It gives a complete picture of the connectivity. Example: Propane (`C₃H₈`) ``` H H H | | | H - C - C - C - H | | | H H H ``` Condensed Structural Formula: A simplified version of the structural formula where C-H bonds are not shown. It groups the hydrogen atoms with the carbon atom they are bonded to. It's a convenient shorthand. Example: Propane (`C₃H₈`) can be written as `CH₃CH₂CH₃`. B. What is a Homologous Series? (Inductive Approach)
Let's investigate a family of organic compounds called the Alkanes. Alkanes are hydrocarbons (contain only carbon and hydrogen) with only single covalent bonds. Let's look at the first four members.
| Name | Molecular Formula | Condensed Structural Formula | | :------ | :---------------- | :--------------------------- | | Methane | CH₄ | CH₄ | | Ethane | C₂H₆ | CH₃CH₃ | | Propane | C₃H₈ | CH₃CH₂CH₃ | | Butane | C₄H₁₀ | CH₃CH₂CH₂CH₃ |